Non-woven mats for use under roads and under railroad track structure along the right of way, are well known in the art. One such arrangement is disclosed in U.S. Pat. No. 3,670,506, dated June 20, 1972 and entitled "Process for Stabilizing Soils", and is directed to a method of utilizing non-woven fabric in poor support areas. Other prior publications include, for instance, an article entitled "Testing of Subgrade Stabilization Fabrics Moves Ahead" in the October 1976 publication of Railway Track and Structures. However, to applicant's knowledge, these prior art mats as used in the environments indicated are of generally uniform thickness throughout. Moreover, such prior art mats are generally one unitary member formed of a predetermined substantially uniform thickness of fabric material, and cut into predetermined lengths for use at the site.
Also in a pending U.S. patent application of Robert Luebke, Ser. No. 092,709, filed Nov. 9, 1979, now U.S. Pat. No. 4,265,398, there is disclosed a variable thickness fabric mat for use under railroad track crossings, switches and the like, which patent application is assigned to the assignee of the present application. Various prior publications including aforementioned U.S. Pat. No. 3,670,506 are identified in said Luebke application, and reference by incorporation is made thereto.
The present invention provides a novel variable thickness mat, adapted for use along a railroad track right of way beneath the track structure, so as to more uniformly distribute the force loads from a train to the underlying bearing support soil, and which will not impede drainage. The mat comprises a thicker central portion which underlies the track structure proper, thereby locating the thicker portion where it is most beneficial to the applied loads, and lateral shoulder portions of reduced thickness, as compared to the central portion, with such lateral shoulder portions projecting laterally beyond the confines of the track structure, and adapted to be covered by the ballast bed supporting the track structure.
Accordingly, an object of the invention is to provide a novel variable thickness mat for use along a railroad right of way beneath the track structure for more uniformly distributing the force loads applied to the track structure due to traffic thereover, to the underlying soil bearing areas, and which will not impede drainage, but instead will actually facilitate the latter.
Another object of the invention is to provide a mat of the aforementioned type which is formed of non-woven fabric.
A still further object of the invention is to provide a mat of the above described type which is comprised of a plurality of layers of fabric material, with means connecting the layers together, to form an integral mat member.
A still further object of the invention is to provide a mat of the aforementioned type which includes layers of non-woven fabric combined with at least one layer of woven fabric, together with means connecting the layers together into an integral mat member.
A further object of the invention is to provide a railroad track structure utilizing a mat of the aforediscussed type.
A still further object of the invention is to provide a method in a railroad track environment of reducing the stresses thereto utilizing a fabric mat underlying the railroad track structure.
Other objects and advantages of the invention will be apparent from the following description, taken in conjunction with the accompanying drawings wherein: